In the 3rd Generation Partnership Project (3GPP) TS 22.060 specification, according to the types of services offered, General Packet Radio Service (GPRS) terminals are divided into Class A, Class B, and Class C, to distinguish their capabilities of handover between a GPRS data service and a Global System for Mobile Communication (GSM) voice service.
Wherein, a terminal of Class A can be attached to a GPRS network and a GSM network simultaneously, and supports the concurrent operation of a packet switched (PS) domain service and a GSM voice service. It is possible to browse a network and receive/send an email while a voice call is proceeding, that is, voice calling and data transmission can be performed simultaneously.
A terminal of class B can be attached to a GPRS network and a GSM network simultaneously, but it does not support the concurrent operation of a PS domain service and a GSM voice service, and can only operate one service at a certain time. Handover between a PS domain service and a GSM voice service can be realized through signaling. For example, PS domain data transmission is temporarily suspended when a call request is initiated by a terminal user, and is resumed after the completion of the call. However, in existing networks, a terminal of Class B is unable to receive a GSM service message, such as a voice call or a SMS message while receiving a PS domain data transmission.
A terminal of Class C only supports PS domain services but not GSM voice services. A terminal of Class C is primarily applied in a GPRS modem, and is not used for PS domain service requests.
The operation of a terminal of Class A needs a large amount of Central Processing Unit (CPU) bandwidth, which results in high cost and expensive price. Accordingly, terminals of Class A are uncommon on the current market. Terminals of Class C are not suitable for PS domain service requests, and thus most of the GPRS terminals available on the current market are terminals of Class B.
During the realization of this invention, the inventors have found that existing terminals of Class B have at least the following problems:
Because a terminal of Class B does not support the concurrent processing of a PS domain service and a Circuit Switched (CS) domain service, when the terminal of Class B is engaged in a continuous reception/transmission of PS domain data during the process of a PS domain service, it is unable to process a CS domain service.
For example, when a terminal of Class B is continuously receiving PS domain data, if a calling user makes a call to a called user, the call request can not be admitted to the called terminal, and the called terminal does not present any prompt except to the called user while the calling terminal will receive a prompt that “the number you dialed is engaged”, which may impacts the success admission rate of a GMS voice service consequently. In practice applications, even if the called user has turned on a missed call reminder service, because SMS and the voice service both belong to CS domain services, during the continuous reception of PS domain data by the called terminal, the missed call reminder platform is unable to send a SMS message notifying an incoming call to the called terminal, and until the called terminal has stopped receiving the PS domain data, the missed call reminder platform can send to the called terminal the SMS message, notifying the called user of the calling number, the calling time and other information of that call the SMS message. If the missed call reminder service is not turned on, the called user cannot be informed about the missed call at all, leading to serious impacts on user experience about the service.